The present invention relates to a disc drive microactuator, and more particularly to a microactuator employing a capacitive position sensor to indicate the relative position of the microactuator rotor with respect to the stator during operation of the microactuator.
The density of concentric data tracks on magnetic discs continues to increase (that is, the size of data tracks and radial spacing between data tracks are decreasing), requiring more precise radial positioning of the head. Conventionally, head positioning is accomplished by operating an actuator arm with a large-scale actuation motor, such as a voice coil motor, to radially position a head on a flexure at the end of the actuator arm. The large-scale motor lacks sufficient resolution to effectively accommodate high track-density discs. Thus, a high resolution head positioning mechanism, or microactuator, is necessary to accommodate the more densely spaced tracks.
One promising approach for high resolution head positioning involves employing a high resolution microactuator in addition to the conventional lower resolution actuator motor, thereby effecting head positioning through dual-stage actuation. Various microactuator designs have been considered to accomplish high resolution head positioning. One successful microactuator design is disclosed in copending U.S. application Ser. No. 09/315,006, entitled xe2x80x9cMagnetic Microactuator,xe2x80x9d filed May 19, 1999 by P. Crane, W. Bonin and B. Zhang, which is hereby incorporated by reference.
In addition to the advances in the movement mechanisms of microactuators, it is also desirable to provide an apparatus to indicate a relative position of the microactuator rotor with respect to the stator. Such an apparatus is provided by the present invention.
The present invention is a disc drive system employing a microactuator and a capacitive position sensor to provide information relating to the relative position of the microactuator. The disc drive system includes a recording disc rotatable about an axis, a slider supporting a transducing head for transducing data with the disc, and a dual-stage actuation assembly supporting the slider to position the transducing head adjacent a selected radial track of the disc. The dual stage actuation assembly includes a support structure supporting the slider in proximity to a surface of the disc, the support structure being coarsely positionable by a main actuator. A microactuator is also provided as part of the dual-stage actuation assembly, including a stator attached to the support structure and a movable rotor operatively attached to the slider, the rotor being connected to the stator by at least one flexible beam. A capacitive position sensor is employed connecting the stator to the rotor, the capacitive position sensor providing a relative position signal representing a state of displacement of the microactuator.